Non-invasive ventilation (NIV) denotes a mechanical respiration assistance or form of respiration in which the patient's airways are accessed via a tightly fitting nasal or face mask (non-invasively) rather than via an endotracheal or tracheostomy tube (invasively). A distinction is made in non-invasive respiration therapy between negative-pressure ventilation (NPV) and positive-pressure ventilation (NIPPV—non-invasive positive-pressure ventilation) with the BIPAP (biphasic positive airway pressure) as well as CPAP/ASB (continuous positive airway pressure/assisted spontaneous breathing) respiration patterns. The present invention pertains to NIPPV in CPAP/ASB.
Non-invasive ventilation is used for the therapy of many different forms of respiratory failure and has found acceptance as an addition to conventional, i.e., invasive weaning from the respirator. The CPAP/ASB form of respiration with NIV is thus used to regulate oxygenation and ventilation disorders.
The use of NIV is recommended especially when patients are extubated after a preceding conventional weaning and nevertheless display a significant hypercapnic respiratory failure. It was possible with NIV in these cases both to reduce the respiration time and to reduce the rate of re-intubations, which increase mortality.
General Advantages of NIV Respiration are:                The patient tolerates the respiration better.        No or only slight sedation is necessary.        The patient can communicate/it is possible to communicate with the patient.        Oral feeding is possible.        The breathing air is humidified in a physiologically adequate manner.        The patient can be better mobilized (e.g., while sitting).        
Advantages of NIV Over Invasive Respiration:                Shorter respiration time.        Shorter stay in the intensive care unit.        Fewer nosocomial infections, especially pneumonia, especially due to re-intubations.        Lower mortality.        Low cost of therapy.        
Prerequisites and Indications for NIV:                The patient must be alert and cooperative.        Respiratory drive as well as swallowing and protective reflexes must be present.        Hemodynamic stability.        Pulmonary indications:                    Chronic respiratory failure                            COPD                Obstructive sleep apnea                Disturbances in respiratory drive                Neuromuscular disorders                                    Acute respiratory failure                            Acute COPD                Pneumonia                Pulmonary embolism                                    Weaning                        Cardiac indications                    Cardiogenic pulmonary edema.                        
The SmartCare/PS respiration option available for the Dräger EvitaXL and Dräger Evita Infinity V500 respirators offers an automated weaning strategy for the CPAP/ASB invasive form of respiration. According to a clinical guideline, the inspiratory pressure assistance (ASB) on the respirator is sought to be minimized gradually and at short time intervals in order to ultimately accompany the patient autonomously until the patient is able to be extubated over an attempt at spontaneous breathing over 1 to 3 hours. Measured data are sent to the knowledge-based system from the respirator every 5 seconds (spontaneous respiration rate, tidal volume, end-tidal carbon dioxide), and the respiration therapy is automatically adjusted with these measured data every 2 to 5 minutes conform with the clinical guidelines and adequately for the patient's status. It was possible to show in a multicenter randomized study that the respiration time can be reduced by 33% and the weaning time by up to 50% with this automatic respiration adjustment.
The above-described SmartCare/PS adjustment method cannot be used directly for non-invasive respiration with the goal of post-extubation respiratory stabilization. The essential reasons for this are:                Unlike in SmartCare/PS, active weaning is not the therapeutic goal in NIV.        Contrary to SmartCare/PS, active attempt at spontaneous breathing is not desired in NIV.        The CO2 measurement under NIV is fragile and can therefore be used only conditionally, whereas the end-tidal CO2 value is an essential input parameter for SmartCare/PS.        Further respiration parameters must be adjusted, besides the ASB.        
In particular, patient-device asynchronies cannot be purposefully avoided with the prior-art method. Leakages, which may be considerable precisely under NIV, are not taken into account in SmartCare/PS. Finally, it is necessary in non-invasive respiration to check the settings more frequently.